Sound record tablet



Oct. 16, 1934. w. H. MILLER 1,976,795

SOUND RECORD TABLET Filed June 2; 195.2'V

' f- |NVENTOR 6 U/aler lik/Iller Il A ORNEYv w vatented Oct. `il 6, 1934 PATENT ori-'Ice 1,976,795 somm nncoan 'TABLET Walter H. Miller, South Orange,

dison, Incorporated, West N. if., a corporation oi' New Jersey to Thomas A. E

range,

N. J., assigner Application .lune 2, 1932, Serial No. 614,922 I till.V (Cl. 274-44) The present invention relates to sound-record tablets and more particularly to hollow cylindrical sound-record tablets such, for example, as are ordinarily used in connection with dictating mad chines or business phonographs, the invention being especially directed to an improved construction or formation of the bore of such hollow tablets.

In order to facilitate the application and re' l@ moval of a hollow cylindrical record or tablet to and from a record Support, and at the same time to provide for irictionally maintaining the record in proper position on the support, it has been found desirable to taper the longitudinal.

llt bore of the record and to provide said bore vwith some form of spaced bearing surfaces. Heretofore these bearing surfaces have lusually been produced by grooving the bore of such a record with a plurality of helical channels generated around the longitudinal axis ofthe record, like the riiing of a gun barrel. Variousrforms of riiling of the bore of the record have been re sorted to by changing the pitch and/or the shape of the lands or projections. However, in all cases the lands and grooves have been extended to the extremity of the larger end portion of the bore of the tablet to enable the core of the mold used in forming the tablet to be readily extracted from -the latter after it sets.A Such a :riiied or grooved record tablet is materially weakened, especially at its thinner end portion, and is likely, upon being applied to or removed from a record,support, to be broken, cracked or 'so damaged as to be rendered unsuitable i'or further use. 'I'he principal object of thisinvention is to produce a record tablet, having a. suitably fiuted bore, but wherein the above described weakening thereof is largely avoided, whereby the danger or likelihood o1' breakage or serious damage to the 40 tablet incidental to vthe operation of applying or removing the same from the record support is practically eliminated.

Another object of the invention is to so reenforce the thinner end of a ried record of this' character as to avoid the necessity of any departure from the ordinary process of manufacturing such records, as well as any substantial changes in the form, size, or composition of the latter.

A further object of the invention is to provide in a tablet such asv described, a suitable re-enforcing liner-in commotion with my improved bore construction, said liner preferably Ahaving centralizing means whereby it may readily be embedded tor a portion of its length concentrically with the' bore of the tablet. p

Other and further features and objects of the invention will be obvious upon an understanding of the preferred embodiment about to be described or will be indicated in the appended claims. Also various advantages not referred @a to herein will occur to one skilled in the art upon employment of the invention in practice.

A preferred embodiment has been chosen for the purposes of illustration and description and is shown in the accompanying drawing, wherein: 65

Figure V1 is a central longitudinal cross sectional view of a record tablet in accordance with my invention;

. Fig. 2 is a fragmentary view, similar to Fig. i, of a record tablet provided with a self-central- 79- izing re-enforcing liner;

Fig. 3 is an end View looking from the left in Fig. 1::

Fig. 4 is a fragmentary end view locking from the left in rig. 2; 75 Fig. 5 is a sectional View taken on line 5-5 of Fig. 1; Y

Fig. 6 is a sectional view taken on line 6 6 of 7 is a View, partly in elevation and partly 8*A in section, of the molding apparatus showing the improved core for forming the bore of a record. and also showing clearly the manner in which a liner may-be embedded in the record;

Fig. 8 is a'se'ctional view of a record taken on a line .corresponding to line 8-8 of Fig. 6; and

,rmly and frictionally engage the bore of the tablet so as to hold the same :for rotation with the mandrel and against longitudinal displacement thereon. 'Ihis mandrel is tapered, and, consequently, the bore ofv the record is correspondingly tapered from the small end 2 tothe large end 3. The taper is provided, among other reasons, to enable the tablet to be easily wlthdrawn from the core of the mold inwhich it is formed, and also so that the tablet may be more readily applied to'and .removed from the mandrel. To .further facilitate the removal o1' the tablet from the mold core and-the application and removal of the sameto and from the mandrel, and alsoto provide ample bearing ensage A ment between vthe mandrel and tablet for Iricv tionally holding the tablet on the mandrel with 119 sufficient firmness, the bore of the tablet is provided with the helical lands, ribs or projections 4 and grooves 5.

'I'he lands or ribs 4 and grooves 5 are produced in the molding of the tablet by a iluted core 6 (se Fig. 7). During the molding operation the core 6 is mounted on a suitable base I as is also the cylindrical mold shell 8 within which the core is centrally disposed. The upper end of the shell 8 is open and in producing a tablet, molten wax or wax-like material from which the tablet is to be formed is poured into the shell through this open end. After the said material sufliciently congeals, the shell 8 is rst stripped from the. formed record tablet, and the latter and the core are then separated by imparting relative rotary movement thereto. After the record is separated from the core, it is allowed to thoroughly set. The record is then reamed to make it more accurately fit the mandrel. In the reaming op eration the inner'or higher portions. of the lands are removed and the surface portion of the bore adapted to contact the mandrel` is therefore increased. f

From the foregoing, it is obvious that the riing in the bores of records of the character described is highly desirable and that to dispense with .such riiiing would result in serious disadvantages. Consequently the present invention is meritorious as it remedies the above indicated weakness of such'tablets due to the extension of the rifling or helical grooving to the thinner end of the tablets, while at the same time all of the advantages of the riiiing or grooved construction are retained.

In a tablet produced in accordance with my invention, the riiling or grooving of the bore is preferably formed as shown in Figs. 1 and 5, with the bottom of each groove 5 for the greater porti of the length of the groove, inclined or ta with respect to the axis of the tablet substantially in compliance with the taper of the bore of the tablet, but with the bottom of the portion 10 of each groove beyond the point indicated at A and adjacent the thinner end of the tablet, parallel or substantially parallel to the said axis. In other words, all points in the bottom of the portion 10 of each groove 5 are at substantially the same radial distance from the longitudinal axis of the record. Thus, the grooves 5 gradually decrease in depth from the points A to the points 11 (Fig. 1) where the bottoms thereof merge in the surface of the bore ofthe tablet.- When a tablet hu the bore construction just described, the core 6 of the mold may be readily extracted from the tablet after this latter has been formed, and the tablet may afterward be teamed in the manner hereinbefore set forth. Also as a result of such construction the tablet is appreciatively increased in strength at its thinner end without sacrificing any of the advantages due totheusualriflingorrib andgroove construction.`

The location of` points A, at which the inclination of the bottom surfaces of the grooves 5 change, may be varied lengthwise of the bore oi' the record cylinder; depending upon the depth ofthe main portions of said grooves and the desired location of the vanishing or merging DOnts 11. If the points. A are shifted to the left, l(lig. 1) the points 11 of grooves 5 will be located nearer to the adjacent end of the cylinder, while if the points A are shifted to the right, the points 11 will be more remote from the said end of the cylinder. The formation of the bore of the tablet is, of course, governed by the construction of the core 6.

It is sometimes desirable that sound record vtablets of the character herein described have re-enforcing liners molded or embedded therein. To produce such a re-enforced record I place a tapered or frusto-conical tube or liner 12, made of a stiff or semi-rigid and porous fabric or foraminous material, over the core 6 of the mold, as shown in Fig. 7. When the lands of'the mold core which form the rifling or grooves in the bores of such tablets extend over the full length of the core, as is customary, such a tapered liner is readily held in accurate centralized position. However, in the practice of my invention, the lands 5' of the core 6 are necessarily changed so that the portions thereof between the points A' and the larger lower end of the core will produce the groove portion 10 in the bore of the tablet. To centralize the liner on the mold core 6 and in the record tablet, I proceed as follows:

'The liner 12, referring particularly to Fig. '7. is preferably provided with a circumferential corrugation or crimp 13 which is formed at such a point lengthwise of the liner, that when the latter is properly disposed on the core 6 such corrugation will substantially correspond in position with the points where the lands 5 merge with the main conical surface portion of the core. The corrugation 13 may extend unbrokenly entirely around the liner or may be interrupted so as to comprise a plurality of spaced sections. The depth of this corrugation is such that when the liner is properly positioned on the core 6 it will, as shown in Fig. 7, be maintained concentrically -thereon. Accordingly, the liner will be embedded in the tablet thereafter formed inthe mold concentrically with the bore of such tablet and at a suicient distance from the surface of said bore to permit the tablet to be properly reamed without interference from the liner and without mutilation of the latter other than the cutting away of part olf` said corrugation. Also, as seen in Fig. 2, an appreciable portion of the liner will be. embedded in and re-enforce the thinner ungrooved end portion of the tablet. It will be lmderstood that when the wax-like material of which the tablet isformed is poured, in a hot Huid condition, into the mold it will pass quite freely through the' porous or ioraminous material of the liner 12 into close engagement with the core 6;

It is to be understood that the terms record and tablet asused throughout this specification, are each intended to refer to a hollow cylindrical phonograph record tablet either before or after the sound recording has been formed there- It is to be understood that various changes may be made in the herein described embodiments without departing from the spirit of my invention, and that all matter herein contained is to be interpreted as illustrative and'not in a limiting sense.

Having thus described my invention, I claim: l. A hollow cylindrical tablet having grooves 1n its bore extending longitudinally of the latter for the greater portion of its length, .said grooves having corresponding end portions which decrease in depth toward the nearer end of the tablet and finally merge with the main, surface of sald bore at points spaced inwardly from but adjacent said end of the tablet.

2. A hollow cylindrical tablet having longitudinally extending grooves in its bore, said grooves 15 having corresponding end -portions which decrease in depth toward one end of the tablet and portions of substantially uniform depth'respectively joining said end portions and extending therefrom towards the other end of the tablet.

3. A hollow cylindrical tablet having a tapered bore provided with a plurality of similar longitudinally extending helical grooves, said grooves having main portions of substantially uniform depth and portions adjacent one end which respectively join said m'ain portions atv one end of the latter and which decrease in depth from such main portions toward one end of the tablet.

4. A hollowcylindrical tablet having a tapering bore, said bore being provided with grooves which extend longitudinally thereof for the greaterpart of its length, said grooves having their corresponding end portions decreasing in depth toward the nearer and larger end of said bore and finally merging with the main surface of the bore at points spaced inwardlyA from but adjacent4 said larger end of the bore.

5. A hollow cylindrical tablet having longitudinally extending grooves in its bore, said grooves having portions adjacent one end which decrease in depth towards one end of the tablet and which merge with the main surface of said bore at points spaced-inwardly from but adjacent to the said end of the tablet, and re-enforclng means embedded in a portion of the' tablet corresponding to the said end portions of the grooves and extending beyond said grooves toward the said the main surface of said bore at points spaced inwardlyfrom but adjacent to its larger. end, and re-enforcing means embedded in a portion of the tablet corresponding to the -said end portions of minating at points spaced inwardly from but adjacent to the thinnerend of the tablet, and reenforcing means embedded ina portion of the tablet corresponding to'a portion of the groovgrooves, said grooves having one end thereof tering in said bore, said means extending beyond said grooves toward the said thinner end of the tablet.

8'. A hollow cylindrical tablet having grooves in its bore extending longitudinally of the latter 10; A hollow cylindrical tablet having a tapered bore, said bore being provided with grooves extending longitudinalhr thereof for the greater portion of its length but terminating' short of each end of the tablet, said grooves having corresponding end portions which decrease in depth toward the larger end of said bore.V

WALTER H. 

